The Grain as a Precious Metal Weight
A grain is a near obsolete unit of weight used for gold and other precious metals, often slighlty deceptively or as hype. Can also refer to metals in granular form.
The grain was ancient unit which was originally based on the weight of a grain of cereal. The grain is the smallest unit of weight in the avoirdupois, troy, and apothecaries systems. Surprisingly it is identical, or has an identical value, in all three systems.
- 24 grains =1 pennyweight
- 480 grains = 1 troy ounce
- 5760 grains = 1 troy pound
- 437.5 grains = 1 ounce avoirdupois
- 7000 grains = 1 pound avoirdupois
- 1 grain = 0.0648 grams (0.06479891)
- 15.432 grains = 1 gram
Although we have stated above that the grain weighed the same in all three of the above systems, there were at least two different grains.
In England, before 1527, the wheat grain was used as the basis of the Tower weight system. The Tower grain was equivalent to 45/64th of a Troy grain.
From 1527, the barley grain was used as a base unit for the English or avoirdupoids weight system.
Since the implementation of the international yard and pound agreement of 1 July 1959, the grain or troy grain (Symbol: gr) measure has been defined in terms of units of mass in the International System of Units as precisely 64.79891 milligrams. 1 gram is approximately 15.43236 grains.
Jeweller's or Pearl Grain
There are, or were, 4 grains per carat, although this appears to be an rough approximation used by gem dealers. As there are 5 carats per gram, this would make a gram equal to 20 diamond grains. The carat was itself based on the weight of a carob seed.
Deception and Hyperbole
In recent years, probably exacerbated by greatly increased precious metal bullion prices, we have noticed many shysters advertising "One Grain" gold bullion bars or ingots. Sometimes the word grain is abbreviated to Gr, probably in the hope that the inexperienced buyer will mistakenly believe they are buying a one gram bar, which although still small, is worth many times more than a grain.
As we wrote this, one grain of gold was worth about £1.60 GBP, €1.90 Euros, or $2.60 USD. At the same time, a gram of gold was worth approximately £24 GBP, €31 euros, or $40 USD.
A grain is so small and insubstantial that they are often stamped out with a hollow back, and packaged in a sealed plastic sheet, so that the buyer cannot readily see how little they have bought.
Mass v. Weight
In this page, we have referred to weight and mass as being interchangeable as though they were the same. They are not, mass is a measurement of the amount of matter in an object. Weight is the force exerted by the mass of the object due to gravitational attraction.
Grain as in Granule
To make life easy for manufacturing jewellers, carat and fine gold is often granulated by bullion dealers, so that reasonably exact quanities can be weighed our conveniently, rather than having to cut pieces of sheet or wire. This is often referred to as "grain" or "casting grain" if it is ready alloyed for jewellery casting.
Weight of Coins Quoted on This Website
This page specifies the units of weight we use on many pages of our websites, with a note about tolerances, etc.
In Gold We Trust!